This research project is concerned with the in vitro synthesis of teichuronic acid by cell membrane fragments of Micrococcus lysodeikticus. Teichuronic acid, a cell wall polysaccharide consisting of glucose and N-acetylmannosaminuronic acid in a sequence of alternating residues, is covalently attached to peptidoglycan in native cell walls. A series of intermediates containing undecaprenol phosphate are known to be involved in the synthesis of teichuronic acid. The reaction product may still be attached to the carrier lipid. This project seeks to demonstrate in vitro the transfer of the teichuronic acid from undecaprenol phosphate to peptidoglycan to form the macromolecular complex present in the cell wall. Characterization of the structure of the linkage region in native cell walls is necessary to show that the comparable linkage is formed in vitro.